Effect of vitamin D supplementation on insulin resistance in patients with hypothyroidism

I.V. Pankiv

Abstract

Background. Over the past decade, numerous non-skeletal diseases have been reported to be associated with vitamin D deficiency, including autoimmune thyroid pathology. Different studies provide evidence that vitamin D may play a functional role in glucose tolerance through its effects on insulin secretion and insulin sensitivity. The effect of vitamin D supplementation on insulin resistance in patients with hypothyroidism has not been investigated. The purpose of the study is to evaluate the effects of vitamin D supplementation on insulin resistance in hypothyroidism. Materials and methods. 47 participants, 32–74 years old, including 39 women (82.9 %) and 8 men (17.1 %), took part in the study. Serum thyroid-stimulating hormone, insulin and 25(OH)D concentration were measured, and HOMA-IR was calculated. All measurements were performed at the beginning and the end of the study. Patients with hypothyroidism received 21,000 IU of cholecalciferol orally per week for twelve weeks. The results were analyzed by descriptive tests, and a comparison between variables was made using paired T-tests or Wilcoxon tests, as an appropriate. Results. All of the participants were vitamin D deficient. Mean serum 25(OH)D concentration was 21.72 ± 6.14 ng/ml. The results at baseline and at the end were: for insulin — 19.36 ± 2.39 and 9.92 ± 2.38 mIU/L (p < 0.05) and for HOMA-IR — 3.91 ± 0.32 and 2.38 ± 0.17 (p < 0.05), respectively. Conclusions. Our data showed significant improvement in serum insulin and in HOMA-IR after treatment with cholecalciferol, suggested that vitamin D supplementation could reduce insulin resistance in hypothyroidism.